Incineration of waste for reduction of volume has generally been conducted at temperatures in the range of for example 1000.degree. F. (538.degree. C.), too low for decomposition of all toxic materials. Even with incineration combustion in higher ranges of 1000.degree.-1400.degree. F. (538.degree.-760.degree. C.) the temperature may be insufficient for complete breakdown of complex or hazardous materials. Furthermore, such temperatures are not as useful for power generation and co-generation of heat as are even higher combustion temperatures.
In waste incinerators the "starved air" or "controlled air" method of trash burning is often used for pyrolysis of waste and for recovery of identified chemicals or pollutants before discharge of flue gasses. A starved air refuse incinerator is described in the Stockman U.S. Pat. No. 3,568,609 having a level bed or layer of sand on the bottom of the combustion chamber. The sand rests over an ash removal opening and is "drained", dropped, or removed from below through the bottom opening to lower the level of the sand and therefore the level of ash accumulating in the combustion chamber. The sand bed blocks air entry or air flow back in through the bottom opening to the combustion chamber, maintaining the "starved air38 combustion conditions.
The Hughes et al. U.S. Pat. No. 3,855,950 is concerned with both continuous loading or feeding of waste fuel and continuous ash removal without changing the controlled air or starved air combustion chamber conditions. Hughes et al. describe "pusher members" for pushing waste material in a chute through a "guillotine type firedoor." A control system operates the hopper loader door, guillotine fire door, and pusher members in the feed chute so that atmospheric air cannot enter the combustion chamber during automatic operation. Similarly an ash pusher at the bottom of an ash drop shaft or duct below the combustion chamber blocks the ash duct when extended to prevent return flow of air. There is no ram or pusher in the combustion chamber itself for removing ash.
The Miller U.S. Pat. No. 4,074,638 describes another pyrolytic incinerator operating on a starved air principal in which there is no air introduced directly into the combustion chamber. Miller describes an hydraulic ram which pushes waste material from a hopper through a guillotine type door into the combustion chamber. Ash cleanout cylinders are described mounted on pairs of wheels on two opposite sides that bear against two sides or opposing surfaces of a housing.
The McRee, Jr., U.S. Pat. No. 4,354,440 describes an under fire air incinerator process in which the under fire system supplies air at less than stoichiometric requirements. An exothermic reaction is created between some of the fixed carbon in the waste material and the starved air oxygen to produce volatiles. Steam is supplied for creating an endothermic "water-gas reaction."
The Stockman U.S. Pat. No. 3,877,589 describes an incinerator loader with waste material compaction drive rams carried on wheels that ride on upper and lower opposing walls of a feed cylinder. The Stockman U.S. Pat. No. 3,863,779 describes another ram type refuse loader in which a complex carriage structure supports the compaction ram. The ram is guided both vertically and horizontally by rollers which bear on the inner walls of an elongate housing.
Applicants have designed an excess air, under fire air, waste fuel incinerator presently operating in Frenchville, Maine. This prior art incinerator is designed to operate in the primary combustion temperature range of 1000.degree.-1400.degree. F. (538.degree.-760.degree. C.) and not the very high temperatures and excess air ranges contemplated by the present invention. Nor does the Frenchville, Maine incinerator incorporate the control system, control methods, and safety features for controlling over temperatures that may occur during primary combustion at such very high temperatures. The present invention also provides additional improvements in waste fuel feeding and ash removal.